The present invention relates to a handy-phone suitable for use in a mobile radio communication network and, more specifically, to a handy-phone of a compact construction having a case containing a built-in antenna.
A handy-phone comprises, as principal components, a low-frequency circuit which handles base-band signals of a relatively low frequency representing information, such as sound signals and computer data, a high-frequency circuit which handles a high-frequency carrier signal for the radio transmission of information, and an antenna. Usually the antenna is a rod antenna which can be pulled out of the case for operation. However, it is troublesome to pull out the antenna from the case every time the handy-phone is used and it is desirable that the antenna of the handy-phone is of a built-in type.
A handy-phone with a built-in antenna as shown in FIG. 6 is proposed in Japanese Patent Laid-open (Kokai) No. Hei 6-169207. In this handy-phone, a low-frequency circuit and a high-frequency circuit are contained in a metal case (shielding case) 2, which will be referred to as "shielding case 2", and an inverted F type planar antenna 3 is mounted on the shielding case 2. The shielding case 2 holding the inverted F type planar antenna 3 is enclosed in a nonmetallic material (case 50).
The frequency bandwidth of the planar antenna 3 is expanded by properly shaping the shielding case 2. If a directional antenna is employed, the directivity of the antenna may possibly be disturbed by a current induced in the shielding case 2. Since the inverted F type planar antenna 3 is non-directional, nothing is mentioned about the disturbance of directivity in the specification of the above mentioned Patent. A slot antenna formed by forming a slot for radiating an electromagnetic wave in the upper wall of a flat conductive box and a micro-strip antenna provided with micro-strip lines are the well-known directional planar antennas. These antennas are advantageous in that the sensitivity with respect to the direction of directivity can be enhanced and the radiation of an electromagnetic wave toward the user's body can be reduced.
The antenna 3 mounted on the shielding case 2 having construction as shown in FIG. 6 increases the thickness of the handy-phone. Since the antenna 3 is disposed necessarily close to the circuit when the built-in antenna 3 is thus mounted on the shielding case 2, the electromagnetic interference of the antenna 3 with the circuit increases. Therefore, the low-frequency circuit is covered with the shielding case 2 as well as the high-frequency circuit, which increases the volume and the weight of the handy-phone.
In conventional handy-phones employing a pull rod antenna, the shielding case for the low-frequency circuit is often omitted. FIG. 7 shows another example of conventional handy-phone. A high-frequency printed wiring board 1 mounted with high-frequency circuit elements is covered with a shielding case 2, and high-frequency power is supplied from the high-frequency printed wiring board 1 through a cable 6 to an antenna 3 disposed outside the shielding case 2. The high-frequency printed wiring board 1 is electrically connected to a low-frequency printed wiring board 4 mounted with low-frequency circuit elements by a connector 5. The shielding case 2 containing the high-frequency printed wiring board 1 is joined to the low-frequency printed wiring board 4 by snapping fingers 7 into recesses formed in the low-frequency printed wiring board 4 and is fastened to the low-frequency printed wiring board 4 with screws 8.
However, in such construction, when the shielding case 2 is thus fastened to the low-frequency printed wiring board 4, a mechanical stress is induced in the connector 5 and there is the possibility that the connector 5 is unable to connect the circuits satisfactorily or soldered parts are broken by the stress.